Dynamic mechanical analysis was first developed in the early to mid-1900s for determining the viscoelastic properties of plastics over a range of temperatures and test rates. Viscoelasticity is the property of a material that exhibits some combination of both elastic or spring-like and viscous or flow-like behavior. DMA is carried out by applying a sinusoidally varying force to a sample and measuring the resulting strain response. By analyzing the material response over one cycle, its elastic-spring-like storage modulus and its viscous or flow-like loss (imaginary) modulus can be determined. Complex modulus is the vector sum of the storage and loss (imaginary) modulus and is used to characterize viscoelastic materials. Because modulus values can be computed for each cycle, DMA is a highly efficient method for measuring viscoelastic material behavior over a range of temperatures and frequencies.
Like plastics, human biologic materials exhibit viscoelastic behavior. As a result, dynamic mechanical analysis can be used to measure the viscoelasticity of tendons, tissue, medical devices and more. Furthermore, because the modulus values for healthy and diseased tissue vary, doctors and scientists have begun using DMA as a diagnostic tool to detect cancer. For the vast majority of medical applications, DMA is being performed outside the body on a bench. As more sophisticated instruments are developed, however, DMA may become an effective diagnostic tool that can be deployed in-situ.